The responses of two different types of aerobic granules to storage, granule A seeded with activated sludge flocs and granule B seeded with pellets (cells), were investigated in this study. After 3-week storage, the surface of granule B remained compact and smooth while obvious crevices were observed on that of granule A. Compared with granule B, granule A had more decrease in biomass concentration, settleability, hydrophobicity, and extracellular polymeric substances (EPS) concentration after the storage. Results indicated that the stability loss of aerobic granules could be related to protein concentration decrease in the TB-EPS fraction and to protein framework disintegration in whole granule. Compared with aerobic granules seeded with activated sludge flocs, those seeded with pellets were more resistant against storage, and thus would have greater potential in practical applications. (c) 2010 Elsevier Ltd. All rights reserved.